Enhanced photocatalytic degradation of Acid Blue 1 using Ni-Decorated ZnO NPs synthesized by sol-gel method: RSM optimization approach

Abstract

In this research, the synthesis of pure and Ni-decorated ZnO nanoparticles was carried out successfully by sol-gel method. The morphology, structure, chemical bonding, and absorption spectrum of the synthesized nanoparticles were investigated using FESEM, TEM, XRD, EDX and elemental mapping, FT-IR, and UV–Vis techniques. After Ni decoration, the spherical structure of ZnO nanoparticles almost changed to uniform hexagonal nanoparticles. The synthesized nanoparticles were used for Acid Blue 1 dye degradation through a photocatalysis procedure under UV light (6 w). The influence of four factors, including metal (Ni) percentage, dye concentration, catalyst dosage, and pH, on the photocatalytic activity of the synthesized photocatalysts, was studied. The experiments were evaluated by means of the response surface methodology (RSM) based on the central composite design (CCD). The experimental results indicated dye concentration = 10 mg/L, pH = 7.77, Ni percentage = 1.117% and catalyst dosage = 1.07 g/L as the optimum values for variables. At optimum conditions, CCD estimated the degradation rate equal to 90.23% which is close to the experimental efficiency, 89.13%, (R2 = 0.9877 and adjusted R2 = 0.9762). The results confirmed the reliability of the CCD to predict the amount of dye removal. Additionally, the Ni-decorated ZnO nanoparticles had more activity in the visible area than the pure ZnO sample. According to the UV–Vis spectra, the band gap decreased from 3.13 to 2.97 eV by adding Ni to ZnO. Furthermore, the Ni-decorated ZnO sample represented a significant redshift compared to the pure sample.